This invention relates to a facsimile transmitter for transmitting picture information, and more particularly to a system for reducing the transmitting time in a facsimile transmission by using the properties of pictures and by eliminating redundancies of pictures of reducing the amount of information to be transmitted and received.
It has been said that picture transmission by conventional facsimile consumes much time, and a wide variety of systems for reducing the transmitting time have been proposed. Of the proposed systems, those using the aforesaid redundancy elimination are called band reduction systems, and such systems have been actually used. Among the band reduction systems, the so-called run-length coding system has been well known and it is expected to greatly reduce the transmitting time. However, such conventional band reduction systems have a shortcoming in that, since the systems have to use digital transmission for sending information because of their intrinsic nature, the transmission is susceptible to various influences, such as transmission circuit characteristics including phase distortion and frequency distortion, noise, short breaks of transmission circuits, and the like. As a result, the rate of causing disturbances in the received picture is fairly high, and it is desired to minimize such disturbances by contriving system constructions which are hardly susceptible to the aforesaid influences. The band reduction systems do not provide direct transmission of the output from a photoelectric converter which scans an original picture or document (to be referred to as the "original", hereinafter) to be sent, but the transmission is carried out only after applying various logic operations to the output signals from the photo-electric converter, so that the circuit construction becomes complicated and a memory with a large capacity is required.Thus, there are various restrictions for utilizing the band reduction systems. In addition, devices for the band reduction systems are expensive.
In view of the aforesaid difficulties of the conventional techniques, the inventors have proposed improved systems for reducing the transmission time which systems are hardly susceptible to adverse influences. The present invention provides an improved transmitting system which enables the optimal use of the previously proposed transmitting-time-reducing system.